This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We will use prepulse inhibition of the acoustic startle reflex as an operational measure of sensorimotor gating. We study the acoustic startle reflex, including prepulse inhibition (PPI) and prepulse facilitation of startle, in Psychiatric and Neurologic patients (Obsessive Compulsive Disorder, Huntington's Disease, Schizophrenia, Impulse Control Disorders, Tourette's Syndrome, and Attention Deficit Disorder), and in appropriate control comparison populations. .